Determining the applied load on the towing hook on vehicles has long been a nuisance for vehicle owners. When connecting a trailer to a vehicle and subsequently loading it with a load, such as gravel, timber, furniture or the like, it is difficult to determine whether the amount of load positioned on the trailer supersedes the amount of load permitted by trailer manufacturer. Likewise, it is difficult to know if the amount of load positioned on the trailer imparts the towing hook with a load which supersedes the amount of load permitted by tow bar specifications, trailer specifications or vehicle specifications.
To measure the applied load on a towing hook, strain gauges can be used. Strain gauges are however problematic as they may have thermal, electric drifting and structural integrity problems. They are further not very good to perceive smaller loads on rigid objects. One way to measure load is disclosed in the published US patent application no. US 2008/011091 A1, assigned to Abnaki Systems Inc. The device disclosed in the Abnaki document uses a resonance force sensor and is said to enable measurements on all forms of structural pre-stress, including axial compressive and tensile loading, applied bending moments, applied torsion, gravitational mass loading.
However, the document is insufficient in terms of that it does not disclose how such sensor should be applied to vehicles to measure load.